Molded Bristle Brushes Comprised Of Helical Segments

ABSTRACT

A molded bristle applicator having a cylindrical core on which are arranged a number of discrete helical bristle segments. Depending on the embodiment, all of the discrete helical segments spiral in the same direction (i.e. clockwise or counterclockwise) around the axis of the core, or some helical segments spiral in one direction and some in the opposite direction.

FIELD OF THE INVENTION

The invention is in the field of cosmetic applicators, and concerns molded brushes whose bristles are arranged in helical segments. The unique bristle arrangements offer new experiences in delivery and grooming of eyelashes and eyebrows.

BACKGROUND

In the present specification, we treat the terms “helix” and “spiral” as synonymous. The properties of helices are well known in geometry. A spiral or helix is a three-dimensional curve that has a central, longitudinal axis. At any point on the helix, the angle between the tangent line and the axis is constant. We can speak of the cylindrical helix in which the radius of curvature is constant, or conical and spherical helices in which the radius of curvature varies continuously. The pitch of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. A double or triple helix consists of two or three (typically congruent) spirals that share the same axis, differing by a translation along the axis.

A brush head with a cylindrical core has a central, longitudinal axis. Many arrangements of bristles on the cylindrical core are known, including spiral (i.e. helical) arrangements. The most common example of spiral arrangement is the twisted wire core brush. In this classic brush, the bristles typically form one continuous helix from one end of the bristle envelope to the other. (The “bristle envelope” is the three dimensional surface defined by the free ends of all of the bristles in the brush head.) Thus, the brush is made up of exactly one helical segment of bristles which always twists in the same direction, from one end of the brush to the other.

In contrast, U.S. Pat. No. 6,341,913 discloses a twisted wire core brush in which a first portion of the bristles spirals along the core in a clockwise direction, and a second portion of bristles spirals down the core in a counterclockwise direction. The two bristle portions meet in the middle of the wire core to form one continuous arrangement of bristles from one end of the wire core to the other. This is unlike the present invention in which the bristles emanating from a core are arranged in multiple discrete helical segments.

Each of U.S. Pat. No. 4,600,328 and U.S. Pat. No. 5,611,361 disclose a dual-brush mascara applicator. Each brush comprises a twisted wire core that has a spiral arrangement of bristles, such that the bristles on one brush spiral in the clockwise direction, while the bristles on the second brush spiral in the counterclockwise direction. For each brush, the bristle portion is one continuous spiral that extends from one end of the wire core to the other. This is unlike the present invention in which all of the bristles emanate from a single core, and are arranged in multiple discrete helical segments, some of which spiral in a clockwise direction and some of which spiral in a counterclockwise direction on the single core.

SUMMARY

The invention includes a molded bristle applicator having a cylindrical core on which are arranged a number of discrete helical bristle segments. Depending on the embodiment, all of the discrete helical segments spiral in the same direction (i.e. clockwise or counterclockwise) around the axis of the core, or some helical segments spiral in one direction and some in the opposite direction.

DESCRIPTION OF THE FIGURES

FIG. 1A is an elevation view of a first embodiment of molded brush comprised of helical segments.

FIG. 1B depicts the brush of FIG. 1A, partially constructed.

FIG. 2A is an elevation view of a second embodiment of molded brush comprised of helical segments.

FIG. 2B depicts the brush of FIG. 2A, partially constructed.

FIG. 3A is an elevation view of a third embodiment of molded brush comprised of helical segments.

FIG. 3B depicts the brush of FIG. 3A, partially constructed.

FIG. 4A is an elevation view of a fourth embodiment of molded brush comprised of helical segments.

FIG. 4B depicts the brush of FIG. 4A, partially constructed.

FIG. 5A is an elevation view of a fifth embodiment of molded brush comprised of helical segments.

FIG. 5B depicts the brush of FIG. 5A, partially constructed.

FIG. 6A is an elevation view of a sixth embodiment of molded brush comprised of helical segments.

FIG. 6B depicts the brush of FIG. 6A, partially constructed.

FIG. 7A is an elevation view of a seventh embodiment of molded brush comprised of helical segments.

FIG. 7B depicts the brush of FIG. 7A, partially constructed.

FIG. 7C is a perspective view of the brush of FIG. 7A, partially constructed.

FIG. 8A is an elevation view of a eighth embodiment of molded brush comprised of helical segments.

FIG. 8B depicts the brush of FIG. 8A, partially constructed.

FIG. 8C is a perspective view of the brush of FIG. 8A, partially constructed.

FIG. 9A is an elevation view of a ninth embodiment of molded brush comprised of helical segments.

FIG. 9B depicts the brush of FIG. 9A, partially constructed.

FIG. 9C is an end view of the brush of FIG. 9A; the varying bristle heights are evident.

FIGS. 10A-10E conceptualize the construction of one embodiment of a brush according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

In what follows, the distribution of bristles on a cosmetic brush head will be discussed in terms of cylindrical helices, but the principles of the invention may be applied to other types of helices, such as conical or spherical.

Referring to FIG. 1A, a brush head (10) according to the invention is comprised of a molded core (1) and multiple discrete helical segments (3, 3′) of molded bristles (3 a) that arise from the core. The core is comprised of at least one straight section and, optionally, one or more curved sections. The straight section of the core is straight, except for slight deviations due to manufacturing tolerances. The straight section of the core is defined by a longitudinal axis, A-A. This axis is also the helical axis around which the helical segments of bristles are arranged on the straight section of the core.

Throughout this specification, when describing the direction of a helical segment of bristles (3 a), the observer is looking down the longitudinal axis of the brush head, from proximal to distal, i.e. from the end that attaches to an applicator stem toward the free end of the brush head. From this vantage point, each bristle segment may twist (or spiral) in a clockwise direction or a counterclockwise direction, but not both. In the drawings, bristle segments that twist clockwise are labelled (3), and those that twist counter-clockwise are labelled (3′), as shown in FIG. 1B.

FIGS. 10A-10E is a conceptualization of the construction of one embodiment of a brush head according to the invention. FIG. 10A shows a core (1) depending from a stem (2). The core is divided in half by an imaginary plane (P1) indicating that the helical bristle segments (3 and 3′) will extend for half the length of the core. FIG. 10B shows the imaginary line (1 a) which is a helical segment whose axis is the longitudinal axis (A-A) of the core. The line (1 a) indicates the position of a first counter-clockwise helical bristle segment (3′). FIG. 10B also shows the imaginary line (1 b) of a second helical bristle segment. The line (1 b) indicates the position of a first clockwise helical bristle segment (3). The bases of the bristles (3 a) will lie on these lines. From one end to the other, each helical line (1 a) or (1 b) makes a ⅓ turn around the core, albeit, in opposite directions, and each line has the same pitch. Thus, in this embodiment, helical lines (1 a) and (1 b) are mirror images of each other through the imaginary plane (P1). In contrast, FIG. 10C shows the situation when the second helical curve (1 b′) makes a ¼ turn around the core. In this case, helical lines (1 a) and (1 b′) are not mirror images of each other. FIG. 10D shows bristles (3 a) formed along the helical lines (1 a) and (1 b) of FIG. 10B. When the process is repeated circumferentially around the core, for a total of 6 times, the result is the brush head shown in FIG. 10E. The number of variations in the placement of helical bristle segments (3) on a core (1) is unlimited. Some of the fully formed brush heads are shown in FIGS. 1A to 9A. To better see the underlying pattern, FIGS. 1B to 9B show partially constructed brush heads.

Feature 1: Direction of Spiral of the Helical Segments of Bristles

Optionally, all of the helical bristle segments in a brush head may twist in the same direction. Alternatively, at least one bristle segment will twist clockwise and one counterclockwise. The clockwise and counterclockwise bristle segments may be arranged in a number of patterns. For example, some bristle arrangements are such that all of the bristles (3 a) on a proximal half of the brush head spiral in one direction (i.e. either clockwise or counter-clockwise), and all of the bristles on a distal half of the brush head spiral in the opposite direction (i.e. either counter-clockwise or clockwise, respectively; see FIGS. 1B, 2B and 6B). This arrangement may make it easier for a user to makeup her eyelashes using only her dominant hand, and/or without having to flip the direction of the applicator. Alternatively, FIGS. 3B, 4B, 5B, 7B, 8B and 9B depict embodiments wherein a proximal and/or distal portion of the brush head supports bristles that spiral in both directions. These arrangements may be better at coating all sides of the eyelashes with sufficient quantities of makeup.

Feature 2: The Longitudinal Extent of a Helical Segment of Bristles

The longitudinal extent of any helical segment (3) may be less than, equal to or greater than half of the length of the bristle envelope. The “bristle envelope” is the three dimensional surface defined by the free ends of all of the bristles in the brush head. The length of the bristle envelope is the distance measured along the longitudinal axis (A-A) from the most proximal to the most distal bristle in the brush head. In some embodiments, every helical segment extends no more than half of the length of the bristle envelope. For example, FIGS. 1B, 2B and 6B depict helical bristle segments that extend longitudinally for a distance equal to half of the length of the bristle envelope, while helical segments that are shorter than half the length of the bristle envelope are depicted in FIGS. 3B, 4B, 5B, 7B, 8B and 9B. And, it is not hard to imagine embodiments of the brush head wherein some of the helical bristle segments extend longitudinally for more than half the length of the bristle envelope.

Feature 3: Pitch of a Helical Segment of Bristles

As noted above, the pitch of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. The present invention includes those arrangements wherein all of the helical segments of bristles have the same pitch, as well as those arrangements in which not all of the bristle segments have the same pitch. The density of bristles can be varied along a brush head by varying the pitch of the bristle helix. For example, on a section of the core wherein the pitch is relatively greater, the bristles will be more sparse compared to a section of the core wherein the pitch is relatively smaller. The effect can be seen in FIG. 6A, wherein the bristles on the distal end of the brush head are less densely arranged due to the greater helix pitch.

Feature 4: Helical Segments of Bristles Arranged in a Mirror Image

The arrangement of helical bristles (3 a) on some brush heads may be such that the proximal and distal halves of the brush head are mirror images of each other. This can happen when all of the helical segments (3) in the brush head have the same pitch and the twist of the helical segments alternates down the axis. For example, in FIGS. 1A and 2A the clockwise and counterclockwise helical segments alternate, and have the same pitch, while in FIG. 6A, the clockwise and counterclockwise helical segments alternate, but do not have the same pitch.

Other bristle arrangements included in the present invention are such that clockwise and counter-clockwise helical bristle segments are dispersed among each other along the length of the core. For example, clockwise helical bristle segments (3) may alternate with counter-clockwise helical bristle segments (3′), along the length of the core (FIGS. 7A, 8A, 9A).

In some embodiments, every bristle belongs to either a clockwise helical segment or a counter-clockwise helical segment, but not both. In some embodiments, one or more bristles may belong to both a clockwise helical segment and a counter-clockwise helical segment. No bristle belongs to two or more helical segments of the same orientation (clockwise or counter-clockwise). That is, bristle segments that twist in the same direction (clockwise or counter-clockwise) do not cross each other; preferably, they remain parallel.

As noted above, a common example of a brush head with a spiral arrangement of bristles is the twisted wire core brush, which is made up of exactly one helical segment of bristles. Preferred embodiments of the present invention are made up of 2-50 helical segments or portions thereof. For example, the brush head of FIG. 7A has 48 helical segments or parts thereof; that of FIG. 8A has 40 helical segments or parts thereof; that of FIG. 9A has 28 helical segments; that of FIGS. 1A and 6A have 12 helical segments; that of FIG. 4A has 32 helical segments; that of FIG. 2A has 20 helical segments.

In a single brush head according to the invention, all of the bristles (3 a) do not need to be the same height or shape. FIGS. 7A, 8A and 9A depict brush heads with varying height bristles. The brush heads described herein are molded by standard molding methods, such as injection molding in one or more plastic or elastomeric materials. A rigid stem (2) for attaching to a handle can be unitarily molded with the core (1). Alternatively, the proximal end of the core can have a hollowed out section for receiving a rigid stem element.

In some embodiments of the invention, the core (1) may comprise more than one cylindrical section, i.e. the core may be bent. In that case, a number of discrete helical segments may be arranged on one or both cylindrical sections of the core. All of the features described above may be applied to each cylindrical section, individually, thus increasing the number of variations of the invention, and the utility of the brush head (10).

In some embodiments of the invention, the core (1) may comprise a curved section. The principles of the invention can still be applied to the curved section, by using the central longitude of the curved section as a the axis of the helical bristle segments. All of the features described above may be applicable. 

What is claimed is:
 1. A molded brush head (10) comprising: a cylindrical core (1) that has a longitudinal central axis (A-A); and multiple helical segments (3, 3′) of molded bristles (3 a) that arise from the core (1), each helical segment being arranged helically around the longitudinal axis (A-A).
 2. The molded brush head (10) of claim 1 wherein all of the helical bristle segments spiral in the same direction around the longitudinal axis (A-A) of the core (1).
 3. The molded brush head (10) of claim 1 wherein some of the helical bristle segments (3) spiral in the one direction around the longitudinal axis (A-A) of the core (1), and others of the helical bristle segments (3′) spiral in the opposite direction around the longitudinal axis (A-A) of the core (1).
 4. The molded brush head (10) of claim 3 wherein all of the helical bristle segments (3) on a proximal half of the brush head (10) spiral in one direction, and all of the helical bristle segments (3′) on a distal half of the brush head (10) spiral in the opposite direction.
 5. The molded brush head (10) of claim 3 wherein a proximal portion of the brush head (10) supports helical bristle segments (3, 3′) that spiral in both directions.
 6. The molded brush head (10) of claim 1 wherein the longitudinal extent of any helical bristle segment (3, 3′) is less than half of the length of the bristle envelope.
 7. The molded brush head (10) of claim 1 wherein all of the helical bristle segments have the same pitch.
 8. The molded brush head (10) of claim 1 wherein all of the helical bristle segments do not have the same pitch.
 9. The molded brush head (10) of claim 1 wherein the helical bristle segments (3, 3′) are arranged such that the proximal and distal halves of the brush head (10) are mirror images of each other. 